This disclosure relates generally to the field of digital image capture and processing, and more particularly to the field of photo-realistic shallow depth-of-field rendering from focus stacks. A camera can adjust a lens stack to obtain focus on an object. A camera's autofocus (AF) system, for example, can automatically adjust the lens stack to obtain focus on a subject. A particular image may have several objects that should be in focus.
A focus stack provides a set of images with a variety of focus settings such that various objects in the image appear to be in focus in different images. Focus stacking combines multiple images having different points of focus to create a final image with better overall focus than the individual images. Sweeping the lens stack from macro to infinity is required in order to ensure that all points in the scene are captured in focus. For example, a camera may capture images with a lens stack at a series of predetermined depths. At each depth, a different portion of the image may be in focus. By combining the various images into a focus stack, the final image will have multiple points of focus.
By its very nature the use of focus stacks requires capturing multiple images, resulting in a tradeoff between frame capture and performance. With a low number of frames, there may be parts of the scene that are not captured in focus, however processing power will be optimal. Conversely, a better result requires the capture of more frames to ensure that all parts of the scene can be captured in focus. However, the more images that are captured, the more processing power is required and memory to store the various images for processing.